text:
Do runways need some special kind of tar or protective layer?
Do runways of the airports have some special kind of tar or protective layer to avoid the wear and tear in comparison to that of the Highways as they need to handle the much high pressure and the weights than normal highways?

An obligatory ref: Marsden mats/PSP

Possibly related: How is the runway pavement chosen?

Airport designers may use any type of material, based on construction research status and local meteorological conditions. Pavements may be flexible or rigid. There is no single technique to protect against wear and tear, and none specific to airports, this is similar to regular road construction.
Information on pavement types at Texas Dept of Transportation.
E.g. a rigid pavement:

FAA provides advisories to help designers. ICAO requires airports to report their pavement characteristics.

(source: Detroit Free Press)
FAA documentation related to pavement design:

Pavement Design & Construction
Airport Pavement Design and Evaluation

ICAO requires member states to report aerodrome-related aeronautical data, including pavement strength. The standardized method is known as the Pavement Classification Number (ACN-PCN) method.
As a critical characteristic of a pavement is the friction, this matter is refined in Measurement, Construction, and Maintenance of Skid-Resistant Airport Pavement Surfaces. This document includes data on rubber removal frequency, e.g.

Busy runway end:

(source: Bridgepoint Road Markings Ltd)
A technique for rubber removal:

(source: Waterblasting Technologies)
This thesis describes how to optimize runway pavements in order to increase friction and how to remove rubber deposit:
Optimizing Airport Runway Performance by Managing Pavement Infrastructure by Samantha Theresa Pinto. Note that:

Rubber accumulation on a dry runway is generally not a problem since
  the rubber interaction between the aircraft tire and the rubber on the
  runway creates traction that may actually improve friction. However,
  in wet conditions, rubber accumulation leads to loss of friction on
  the runway by clogging the pavement texture and creating an especially
  slick surface with minimal drainage capability when the runway surface
  is wet. Additionally, rubber accumulation causing decreased friction
  values means pilots have less directional control of the aircraft than
  expected on a bare and dry runway.

Note that some surface materials are less ideal than others.  There's a set of photos out there showing the results of a 737 doing an engine run-up on paving bricks.

Thank you for the quote from the thesis. I was wondering about that since I'm an F1 fan, and one of the biggest issues they have is going to an infrequently used track and waiting for it to "get rubbered in". I.e. get enough rubber on the track that the tires will get improved traction. Of course, if it rains, they run a "wet line" which avoids the rubbered part of the track, because it's very slippery. I had been wondering and was going to ask the difference - I guess there isn't one.

This is to please @Mark and everyone! Caution, bricks crossing at low altitude :-(

To withstand the heavy loads of heavy aircraft landing, the runway mainly needs sufficiently strong foundation and that can be done by simply making it sufficiently thick. Concrete is recommended for airport accepting very heavy aircraft like A380, but it's not always an option because concrete is very rigid and thus requires stable ground and some airport, like the new Hong Kong International Airport built partly on reclaimed land, don't have that luxury.
For surface wear, note that while a runway experiences heavier and faster movements, there is much fewer of them than on a busy motorway.

Nothing special is needed for light aircraft.  Most don't even require a paved surface.  Western airliners  and military are happiest on thick concrete surfaces.  Most Russian airliners and military aircraft with their bigger wheels/tires can operate from dirt runways.

Small aircraft definitely don't need but my question is more specific towards Jumbo jets like A-380 or B-787s.


text:
Why does the MH370 ATC transcript never mention QNH? When is QNH given to aircraft?
Looking at the ATC transcript from MH370, I noticed that nowhere is the QNH communicated to the aircraft. That seemed odd to me... it seems that every time I talk to a tower or airways they tell me what the QNH is in their location.
So, is it normal for airliners to not be told what the QNH is before takeoff? Or in communications with DEPARTURE or RADAR?

It's normal that they don't communicate an altimeter setting if you let them know you have the current ATIS information. Once you climb into the flight levels you don't need it anymore.

Airline pilots generally get the QNH from the airport ATIS or similar. If they don't get it from there, ground control will give it before taxi.
Above the transition level (11,000 feet (3,350 m) in Malaysia, 18,000 feet in the US), the altimeter is set to the standard pressure (29.92 inHg, 1013 hPa), also referred to as QNE. It doesn't take that long to climb through this point, so they would keep the departure QNH set until reaching the transition altitude. They won't need to set it again until they begin their descent near their destination.
So after setting it before taxi, the next time they would need it is on approach before they descend below the transition level. Again, they can get the ATIS from their arrival airport for QNH. If not, the approach controller will give them the QNH.

You can also figure out the QNH by simply setting the altimeter to the airfield level.

@GdD; while true, ATC are required to tell you what the local QNH is unless you tell them you already know it (by stating you have received a particular ATIS information)

QNH and other airport information is communicated to incoming flights through ATIS.
The only acknowledgement of this you will hear through ATC is aircraft first contacting the controller saying "with information Oscar" or similar, which means they have already heard the ATIS bulletin.

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text:
Are there any accurate books that help with identifying aircraft when planespotting?
I want to start planespotting and I'm looking for the best and mosts accurate registration book.
I want this book to be:

accurate
checkable (to check planes I have seen)
have almost every plane
codes (IATA | ICAO)

If anyone knows a book I would love to hear it!

I was going to downvote this question because book recommendation questions are generally considered a bad idea, but on second thought, aviation is small enough that there might just be one accepted canonical reference guide for something like this.

The best option is probably Jane’s Aircraft Recognition Guide. It is hard to find, but it has a large number of planes and has multiple editions.

The Jane's guides are easy to find online: http://www.amazon.com/Janes-Aircraft-Recognition-Guide-Guides/dp/0061346195/ (you'll also find the military guide, and the airline (livery) guide if you hunt around.

I confirm the best option is the one proposed by Peter and voretaq7
However [personal opinion], I think it won't fulfill three main requirements in spotting :

precision
contains almost every plane
portable

I have the french version of that book (because I'm french speaking)

Precision
Precision is what you need to spot the differences between an A318 and an A319 (or a 737-600 and a 737-700) for example. Using the number of passenger windows count/number of exits. Knowing for example a 737-300 can have winglets and no cockpit eyebrows since a dozen years avoids confusion with a 737-700 by looking at the other differences (engines, tail height/size, wingspan, wingroot, flaps slats, spoilers, no winglets wingtip, stabilizers, etc.)
Details you don't have in that book, but you rather gather by experience and curiosity elsewhere.
The book just provide you - per featured model -

one arbitrary picture of the plane (sometimes granny)
one 3-views, mostly left, top (or bottom) and front.
a brief historic description
a non exhaustive list of most common produced versions in bold with one specific information that makes this version different from others (mostly the operation type like "cargo version", or increased MTOW..)
a non exhaustive list of weapons for military aircraft, role and operators if a few countries operate the model.
a resumee of its caracteristics (seats, payload, speed, range)
its dimensions (wingspan, overall length, height)
and a brief way to describe the general looking of the plane (hight/low mounted wings, engines location, model and manufacturer, number of fans for propellers, stabilizers location, one very noticeable caracteristics if any like domes, fuel pods, cargo pod..)

The arbitrary picture can help recognising the aircraft, but seen from other directions, it doesn't help much.
By experience, 3 views doesn't well represent 3D or field depth, as every component is flattened on a drawing (I'm modeling 3D airplanes/Aircraft profiles) Note : some drawings in the book contains minor errors.
The historic description is of no real use in spotting.
Today, model versions are not really relevant, since most aircraft are customizable (mainly commercial aviation) Military aircraft are usually multirole. This kind of information is only useful for someone actually operating/working on the model (ie a pilot or engineer or reproducing the model (3D/scale model)) Weapons loadings greatly vary per mission.
The general looking description is too broad/vague to get a perfect match. Its purpose is more to class a given model in a group of similar models to narrow the identification process to one or two dozens of aircraft than precisely describe the model.

Every plane ?
Impossible ! The book contains commercial, military, fixed wings, tiltrotor, general aviation, utility... It doesn't even contain soaring light weight planes. And you already have several hundreds models.
Some models has to be merged to fit in a single page, like the 737NGs, A330s, B767/777, ERJ17x/19x... (And I'm not talking for military ones)
Of course, most common models are covered, but if you're spotting a Bizjet landing in Heathrow it could take a while before you can clearly confirme it's a Gulfstream V rather than a Gulfstream IV. Worse, when you're looking for single engine propeller. Even worse if the aircraft you're spotting isn't featured in the book, then you could assume it's model X while it isn't.

Portable ?
To have every planes and be precise, you'll end with the encyclopedic version which is actually two very large books with hundreds of pages. You'll look weird bringing those with you while spotting, and it will take even longer to parse it to find your model...
ie : don't !

What I mean is, you can't have enough info in a book that will really help you identify any airplane on first sight.

Dont mistaken me - note for others aswell :
This book is an extremely valuable one and is worth its price, really !
  I'm enjoying it very much and has proven useful countless times for me.
...but not in spotting !

This book is the best option I know.. as a book.
I'm just answering the question "Looking for the most accurate planespotter book" and this book is the one that approximates well the OP's requirements.
But honestly, I think no book will ever fit your needs, unless it's an application on a tablet you can do queries, and contains a huge database of planes in the world with enough informations. I'm not aware of such any application (because I don't have/use/like tablets)
Otherwise :
If you have time to read a book, I would rather suggest to spend that time to visit some spotting sites like Airliners.net or Planespotters.net, forums like Airlinercafe.com aswell as manufacturer's websites, looking for technical documents in PDF format.
Identifying a plane at first glimpse is not a matter of having a tool doing it for you. It's more beeing used look at that plane from different spotting angles, noticing the bits that makes it different from other models, and memorizing that.
And, there are some useful informations you can get by not reading a book but, rather crawling the web (unless you're a collectionneur that has bought thousands books, one dedicated to a particular model) For example, I always had the feeling there was something weird between the Boeing 707(-320) fuselage and the 727s/737s ones. But I couldn't find out what until I read somwhere that "since 727s and 737s are rather short/medium ranges models, it wasn't required to have as much space in the cargo belly. Boeing decided to shrink the lower part of the fuselage." That's why 707 noses looks "sharper" than 727/737s...

PS : each page of the book is rather filled with datas. You don't have much space to add notes, but you can mark a cross though that means you've spotted the plane :) But it would only apply to the (few) pages of the models flying in your region (unless you're a serial traveller and international spotter...)
The book doesn't have IATA/ICAO listing of each airplane. It's rather intended to lambda aviation enthusiasts than the few looking for such specific piece of information.

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text:
Why do some towers reference departures by compass direction, others by leg of pattern?
Got my Private about 6 months ago, and I've always wondered - let's say I request a VFR departure to the South, with the active runway being, say, 2. Some towers will give my departure clearance in reference to the requested compass direction, i.e.
    cleared for takeoff runway 2, right turn to heading 180 approved
whereas other towers will reference it to a pattern leg, such as cleared for takeoff runway 2, right downwind departure approved. Similarly, I've noticed pilots based at airports that use the latter convention will follow that convention when making their departure requests. Is there any rhyme or reason behind which convention a tower follows?

@SentryRaven Are we sure this is in relation to FAA regs? All indications seem to suggest it, but not seeing that definitively. Am I overlooking something? Chris, are you asking from the context of operations under the FAA?

@JonathanWalters Yes, as 7 out 5 EASA CAA / countries use mandatory reporting points to enter or exit a CTR. Departures via  headings or downwind departures are not commonly used here. That sounds like FAA phraseology to me, but I can be wrong there...

@SentryRaven It's common shorhand at some airports (my home field included), but as far as I'm aware it's not officially recognized phraseology (at least the phrase downwind departure doesn't appear in the Pilot/Controller Glossary - I didn't look at the ATC Phraseology order though).

Maybe the OP will clarify... :)

Ah yes, apologies for not clarifying. Looking for an answer under FAA regs, or at least in the context of the US. I asked my old CFI and she said that sometimes a new controller will use a different phrasing than is common at the airport, so it may be as simple as "that's how it's always been done around here", but I'm curious to know if it's more formal than that

@FreeMan Finally someone noticed! :D

Well, 5 out of 4 American adults aren't good with fractions, so I can see where it might have taken some time... ;)

It depends on local custom.
Some airports have multiple runways, so controllers will use compass points instead of pattern legs, and this habit will carry over when they are assigned to a single-runway airport.
Other airports have noise abatement procedures which have specific names. Below are the departures for San Carlos airport, and pilots are expected to use a named departure, such as "Belmon Slough Departure" instead of "right-crosswind departure," and tower will readback the named departure.

From my experience, tower controllers are always being trained to use consistent phrases to make instructions clear at their airport, but in the end you are dealing with humans trying to communicate what they want you to do and what the limits of your clearance are.
To me, it is more relevant to your question that one controller is using a specific heading for you departure and the other referenced the local field downwind pattern.  For your 1st example you are expect to turn to the specific heading of 180 and then proceed on our VFR departure.  For your second example all you have to do is turn toward the downwind leg and then proceeded on your departure, giving you more leeway.
Keep in mind you are departing VFR so I wouldn't overthink it so long as you are complying with specific instructions.


text:
What are the reasons for using an instrument approach on a clear day / CAVOK?
As a new VFR pilot, I was wondering why anyone would fly (or be assigned) an ILS (or other) approach in clear weather?
I ask this because I watched Vienna - Tokyo (Narita) on PilotsEye.tv where the F.O. flew the approach looking at the display all the way until the flare. The visibility was good. Runway 34R.

There are actually quite a few reasons to fly an instrument approach, especially one with vertical guidance (like an ILS), even if the weather doesn't require it:

It serves as a backup to the visual approach.  There are various visual illusions that can cause a pilot to fly an approach too high or too low and monitoring the vertical guidance can help to mitigate those.
It helps to ensure that you land on the correct runway, and even at the correct airport.  (Unlike this airplane.)
ATC uses it when pilots do not have the airport or runway in sight.  This happens quite frequently at large airports where they have to line many aircraft up on final.   The last guy is a long distance from the airport so may not be able to see it but can fly the approach.
It can be useful if it is hazy or the sun is making it hard for the pilots to find the airport.
Some parallel runways are approved for simultaneous approaches (as is the case at Narita for runways 34L & 34R) so ATC will clear two airplanes for the respective ILS's.  This keeps them tracking the centerline of the approach instead of maneuvering visually where they might drift over into the way of the other airplane.
Flying the approach on the autopilot leaves more time for the pilot to focus on other things and possibly catch something that might have been missed while hand flying a visual approach.
Sometimes instrument approaches are used for noise abatement reasons.

If I had to guess about the particular approach that you mention, I would say that it is probably company SOP (Standard Operating Procedures) to fly the ILS whenever possible for the safety benefits, and that Narita allows simultaneous parallel landings to the two runways so ATC would require it as well.

I was wondering if it might have to do with how short Narita's 34R is. Your answer seems to say that could be a factor.

@greener I would say that they are all factors.  I also added one more paragraph which would apply at this specific airport (which I noticed after I reviewed the approach plates).

There are three reasons I can think of:

Noise abatement
I know that it is not allowed to fly visual approaches at many european airports due to noise abatement. They prohibit it to avoid aircraft flying over residential areas left and right of the approach path
Traffic flow
At many international airports (e.g. Tokyo) they have to use every second to manage the huge amount of traffic. Lining up the aircraft on an ILS with an assigned speed is the most efficient way.
Practice / Safety
There are many airlines which tell their pilots not to do visual approaches. This should enhance safety (stabilized approaches) and keep the pilots well prepared for low visibility operations. Sometimes you even practice autoland in VMC to keep current.

Noise Abatement is an interesting one -- at my home field the instrument approaches are actually discouraged for reasons of noise abatement (the nice long straight line toward the runway takes you directly over people's houses). #3 strikes me as a double-edged sword (Asiana 214 as an example).

@voretaq7 I too have seen instrument approaches (and more often instrument departure procedures) used for noise abatement reasons.  It depends on the area surrounding each airport.  #3 is very valid, but it can be taken too far.  Just ask the crew of Asiana 214....  The FAA issued an InFO awhile ago about making sure that pilots practice visual approaches from time to time instead of relying on the automation.

@voretaq7 I myself live below the straight-in approach of a bussy airport. Even though our national AIP prohibits visual approaches for aircraft heavier than 5.7 tonns at this particular airport. This is obviosly done to avoid the majority of residantial areas. I also see a huge difference, between european and american procedures. My poits are honestly based on the other european point of view. Airports fulfill many noise abatement regulations and the straight in approaches meet those restrictions very well.

@Falk We have instrument procedures (frequently Departure Procedures like Lnafziger mentioned) which take noise abatement into account in the US too - the procedures in the New York area generally seem to be less concerned with that though (probably because no matter where we send the plane it's still going to fly over someone's house, so there will still be complaints :)

How is flying the ILS more efficient than a visual approach? A visual approach has much less separation distance than an ILS approach.

In addition to serving as a good cross-check for the visual procedure (which is probably the case here - one pilot looks down, one pilot looks out) there's at least one other reason I can think of for a pilot to request & fly an instrument approach:
In order to maintain currency to act as pilot in command under instrument flight rules a pilot must log a certain number of instrument approaches within a given calendar period (in the USA it's 6 approaches in the last 6 months, plus "holding patterns; and Intercepting and tracking courses through the use of navigation systems.", except for gliders which have a different requirement).
All other things being equal, if your currency is about to lapse you might request to fly an instrument approach (including one turn in a holding pattern) on a VMC day (with a view limiting hood and a safety pilot on board) to maintain currency on.

Umm, if it is VMC you can't log an instrument approach for currency purposes unless you use a view limiting device (which is usually prohibited by the airlines).  See What are the weather requirements to log an instrument approach? for more details.  Also, most airline pilots visit the simulator on a regular basis so instrument currency isn't normally an issue.

@Lnafziger True - airline folks have other ways of maintaining currency. For us flibs you usually buy your (rated) friend a burger in exchange for sitting in the right seat while you're under the hood - I'll update to clarify that :-)

$0.02 to add to all that. The question can be extended a little and one could ask 'why fly ifr on beautiful clear day'. Added safety. For a new instrument pilot it would still be a good practice to operate in the ifr system even if you can't log the flight for currency purposes.


text:
Why does the static pressure inside the cockpit vary from outside static pressure?
When the static ports are blocked, pilots use the alternative static soure and it measures the static pressure inside the cockpit. And it is said that the static pressure inside is lower than the outside static pressure. I wonder why does this happen? Because you know cockpit is blocked from outside and how does the venturi effect applied inside the cockpit and static pressure inside?

Related question

@DeltaLima Good find!

On some light aircraft without alternate sources, breaking the glass on the VSI or altimeter will give you close enough readings to get downstairs safely.

@Simon the VSI is usually preferred: When you smash the glass there's a good chance that whatever you used will also smash the face of the instrument, and losing your VSI is less critical than your altimeter. (VSIs also generally cost less to replace.)

You're referring to this statement in the Pilots Handbook of Aeronautical Knowledge, Page 8-11:

Some aircraft are equipped with an alternate static source in the
flight deck. In the case of a blocked static source, opening the
alternate static source introduces static pressure from the flight
deck back into the system. Flight deck static pressure is lower than
outside static pressure.

The reason for this error with alternate static source is that the air flowing around the airframe creates a slight vacuum inside the airframe, thereby lowering the barometric pressure and generating erroneous readings in the pitot-static system.

The physical effect that causes this drop is call the Bernoulli Effect.
To compute anything reasonable, you would need to use the Compressible flow equation. From this point of view, it would be easier to measure the difference and put it in the instrument failure manual.
In short for the effect: gas with the same density presses against a non-moving object less than against a moving one.

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text:
Can commercial aircraft dump luggage or cargo mid-air?
In a situation where the pilot realizes that weight of the aircraft is too high, can they dump luggage / cargo mid air, similar to dumping fuel?

For some reason I'm finding the image of an airplane pilot surreptitiously dumping the contents of the cargo hold to reduce weight hilarious!

And what's next, "Can airlines dump passengers or flight attendants mid-air"?  Oh my, I'm having trouble breathing here...

My question may seem stupid, but I have heard tales where airlines crashed due to excess weight.. So this led to my question...

This would be a nice feature for handling yappy little dogs.

Dear sir, your luggage is somewhere in Kansas. Sincere apologies, [signed] Delta.

Since the most likely time the pilot would notice the overweight condition would be shortly after takeoff when the plane is likely still over a populated area, I would think that safety concerns for property and people on the ground would prevent the plane from intentionally dropping heavy objects to the ground.

"I have heard tales where airlines crashed due to excess weight.."  I challenge you to cite any verifiable examples.   Small GA planes may get their weight wrong.  Airlines never do.

And if they do they don't stay off the ground for long.

@abelenky: In fact, in 2009 or 2010 an Emerates A340 with 300 passengers on board "got the weight wrong", did a tailstrike on takeoff and broke some things, and then dumped fuel to land again. There was no need to dump luggage. In fact, a mechanism to dump luggage sounds like a great way to make the airplane heavier and have less cargo capacity, plus points of failure.

@dotancohen:  You almost got me. :)  It didn't crash, but it is an otherwise horrifying tale:  http://en.wikipedia.org/wiki/Emirates_Flight_407

Even if they could jettison cargo mid-flight, what good would it do? Being overweight is mainly just dangerous on takeoff and landing. In particular, it can cause the 'landing' to occur immediately after the takeoff, as was almost the case with EK407. If you can takeoff and climb out successfully, then being overweight shouldn't be an immediate safety concern until you're landing. It will, of course, burn fuel faster than anticipated, which might force a diversion, but it shouldn't cause a crash. Also, EK407 wasn't overweight; they just calculated takeoff power incorrectly.

@Michael There's a scene from a John Wayne movie (The High and The Mighty) where the copilot chucks luggage out the back door of what I believe was a DC-4. Of course we're talking a propeller-driven unpressurized piston aircraft in that scenario, which is probably not what the OP had in mind when they posted this question :)

@abelenky One of the reasons for the crash of Air Midwest Flight 5481 was a stall due to excess weight: http://en.wikipedia.org/wiki/Air_Midwest_Flight_5481

No they can't. The cargo doors are secured and will not open mid-flight.
Cargo holds are usually pressurized so opening the door anyway would cause depressurization.
Also if the weight was too high the pilot should never have lifted off in the first place.
Then after you theoretically throw the stuff off board think about what happens after to the stuff. It will drop down hard probably on someone's roof.
Only some military cargo planes with a back hatch are designed to jettison cargo.

So your answer is no... and yes...

@CGCampbell for airliners it is no, for specially designed cargo planes it is yes.

Thanks.... But there would not be much effect of de-pressurization if altitude is low... say 8k feet

@ratchetfreak AFAIK, those cargo planes also have people in the cargo bay to handle the drop (or to jump themselves, in the case of paratroopers); it's not something they can do from the cockpit.

@cpast - that is correct

I believe that the DC-10 had cargo doors that could open in mid-flight. Not that it was intentional!

@dotancohen Also, the early 747s.

Well they did it once at least. A hijacker parachutted?!! from a 727 in 1971

@jean That was via the stairwell in the tail cone from the passenger cabin, not the cargo hold.

@jean and that avenue was closed right after

"Also if the weight was too high the pilot should never have lifted off in the first place." Your answer seems to ignore the fact that sometimes airliners do find themselves overweight once in the air, and have fuel dump nozzles designed to handle just this situation.

@raptortech97 Different consequences though: Dumping fuel (via the dump nozzles) atomizes the liquid into the atmosphere. It's none too good for the environment, but it evaporates away long before it reaches the ground. If you chuck someone's Samsonite out of the plane it's going to be a solid mass of suitcase when it gets to the ground - with the airline's luck it will probably hit someone's new Lamborghini roadster.

Military cargo planes are designed to drop cargo (including humans) as regular operation, so I think it can't be counted as emergency dump. Just like road sander operation can't be called as "emergency jettisoning of cargo".

@raptortech97 that's usually because they have to divert and are too heavy to land safely rather than take off safely. While there have been instances of taking off overweight (sometimes with bad results) those stem from bad weight calculations rather than deliberately taking on too much cargo most of the time.

There are various examples in history where luggage and/or cargo was dump during flight to reduce weight:
Embraer EMB-110P1 Bandeirante, 29 July 1998:

To lose weight, the left overwing exit was opened and luggage of the passengers was jettisoned.

Lockheed L-149 Constellation, 29 May 1972:

Cargo was jettisoned, but the aircraft continued to lose altitude.

Today? No, not practical... aside from sudden depressurization, the high speed of the aircraft means that anything jettisoned from the aircraft stands a chance of striking tail surfaces with enough force to damage or destroy them.
Same goes for the cargo hold - it is also pressurized, with similar problems on sudden depressurization. Unintended opening of the cargo hold in flight has caused more than one crash, and several emergency landings.
In the early days of commercial aviation, dumping luggage due to low fuel was not unknown. In those days, aircraft were unpressurized, and flew through the weather, not over it. Aircraft speed was low, around 100-150kts, so things could be tossed out without risking damage to the tail. The lack of ILS at airports meant that those airports would close more frequently due to poor visibility. It was possible for an airliner, even with good fuel reserves, to run low on fuel if heavy fog closed all airports within the range of the aircraft. One way to keep the plane in the air longer was to dump luggage to lighten the aircraft.
In his book Fate Is The Hunter, Ernest Gann describes preparing to dump luggage from an ice encrusted DC2 - up to four inches thick in some places on the aircraft. They didn't take that step, but were prepared to.


text:
How does banner tow attach and release work?
Planes can sometimes be seen towing banners around large cities or events.
How is the banner attached for takeoff?
How does the plane land after towing a banner?

There are actually a couple of different towing mechanisms out there. You've got your traditional banner pick, with the ropes and the hooks and all that, but there's also a new type of billboard mechanism that allows a tow aircraft to take off with the billboard already attached; it unfurls as the aircraft gains altitude, and can eliminate a potential inefficiency in the process (some days are worse for banner picks than others due to high winds, turbulence, etc.), but it limits the tow aircraft to some pretty small billboards and letter banners are pretty much a no-go.
Talking about the traditional method of banner towing, there are a couple of things to cover.

The banner/billboard setup on the ground - they will be attached to a tow rope (usually about 200 feet long) with a loop at the end. This loop is strung out between two poles a small distance apart. The goal of a banner pick is to have the hook pass between the poles, thru the loop; do that and you will be able to pick the banner off the ground. The banner or billboard will be laid down upwind of the poles (with the tow rope fully extended), so that the pick takes place into the wind; the lower ground speed will help with timing and allow the banner or billboard to come off the ground more smoothly. A small windsock is a common addition next to the poles to make it easier for the pilot to spot them and to give some local wind information. The banners and billboards may be set up parallel to a runway (usually the active runway), or there may be a designated spot elsewhere on the field.
The hook itself is attached to aircraft with a tow hitch and it is possible to have multiple hitches on the same aircraft (highest number i ever saw was 4 on a Piper Pawnee); they get used sequentially i.e. drop the hook, pick up the banner, fly the banner, drop the banner, drop the next hook, pick up the next banner, fly said banner, and so on until you run out of hooks. Most of the time, hooks that are not in use will be tied down somewhere accessible to the pilot who will drop them manually. That Pawnee I mentioned earlier, however, had the hooks attached to hitches on the aircraft's belly, from where they would be released with a switch, so there's more than one way to skin a cat. The hooks are normally attached prior to engine start and the pilot needs to make sure there is no slack in the line, to avoid it becoming entangled in rudder or elevator cables (more on that later), or other assorted bits and pieces of equipment.
Banner tow procedures

Take off is normal, but depending on your hook and cockpit setup, you may have to hold the hook in your throttle hand as you're taking off (this was the case with the Husky I towed in). Be careful not to hit anything with it.
After climbing through about 50 feet AGL, side-step the runway, and drop the hook. Procedure varies depending on your setup, but we used to extend the arm holding the hook as far out the window as we could get, give a gentle tap on the rudder to kick the tail out of the way and toss the hook outwards and away from the airplane. Kicking the rudder was important due to the way the rudder control cables ran in the Husky; we had one pilot who didn't and nearly wrecked when the rope got fouled around the cables, forcing a rudder hard-over once there was tension in the line after the pick - fortunately he was a big guy and the runway was sufficiently long that he was able to overpower the rudder and make a safe landing. Tossing the hook outwards is important lest it get caught up in the propwash and bang against the skin of the aircraft. Again, this happened (wasn't me though).
Coming around for the banner pick - depending on where the banners are set up, you may end up flying almost a regular traffic pattern, but it usually happens at much lower altitudes (5-600 feet) and the banner tow waiver may require that you avoid flying over populated areas to do so, so you may end up flying, say a right-hand pattern instead of your regular left. Either way you end up doing it, you want to end up downwind of the poles, similarly, if you will, to coming in for landing.
The actual banner pick - this is where you'll see a lot of variation. Some outfits will come in flat, just above the poles and pull up once they pass them (unusual, but some do it that way), others will come in high and dive towards the poles, and pull up once past them (it's very pretty and dramatic, but not a lot of room for error IMO). We used to be a bit more sedate about it, and came in as if for a landing, with the goal of touching down at the top of the banner (i.e. the end nearest to you). Obviously, you have to correct for crosswind, which you can do by shifting your line left or right depending on wind direction; the goal is to place the hook, which is trailing behind you and getting blown about by the wind, between the poles. Either way you do it, once you pass the poles, you pitch up immediately to at least 45 degrees or so, and apply full throttle. You zoom climb to about 200 feet AGL and then reduce the pitch angle to be able to maintain a slow-speed climb. Do this right and the banner or billboard will come smoothly off the ground; you may feel a slight tug as tension is applied through the towline if you haven't been smooth enough and ended up yanking the banner off the ground. Continue to climb to whichever altitude you've planned for and, when stabilized in the climb, try to take a look behind you (if you can) to make sure you've picked successfully and that the banner didn't get damaged or something. If you can't look behind you, you can check during a turn, or have your ground crew radio/text and let you know.
Fly the banner - you want to fly slow enough to avoid stressing the engine, airframe, tow rope and banner, but not quite so slow that the engine can't get enough airflow to cool down (remember, on the backside of the power curve, power required increases the slower you try to fly). Watch your altitude and distance from people and objects (the powers that be are quite serious about it), look out for towers (especially those that come with guide cables and the like), high rise buildings, and other traffic, and try not to get too bored flying in circles for hours.
Drop the banner - when you come back in to drop the banner, the goal is to drop it low enough to the ground that the wind won't have time to blow it away onto  active runways (or into the trees - I had to help pull somebody else's banner out of the trees once, not fun). Ideally, you might want to drop it as close as you can to where the ground crew has their bags and everything setup to spare them having to haul heavy banners and billboards over long distances. You release the hook using a lever bolted onto the floor of the aircraft and then apply power, climb out, and come around for another pick or a landing, whatever the case may be.

Hope this helps, let me know if you'd like to know more about any of this.

The basic procedure goes like this:

A flying airplane with a tow hitch mounted to its tail, which acts as the attache point for the grapple hook/cable and the release mechanism.
Those grapple cables are attached to the tow hitch, and runs up the side of the airplane. The hook is hanging in the door and the cable is tied off on the strut, so that it has an easy to release knot. There can be multiple grapple hooks.
The pilot grabs the hook, pulls it to untie the knot, and throws the hook out and back.
After the banner is picked up and the flight, the pilot release the grapple hook and cable from the tow hitch by using lever which is mounted in the cockpit. The process can start over again.

This can be seen in this and this videos.

Thanks, Farhan, now I'm wasting all sorts of time watching those videos... :/


text:
How do I get flight numbers?
Flight AWE685 goes from Seattle to Philadelphia.
What exactly is that AWE685 identifier called?  Every flight seems to have a unique name.  I'm trying to learn more about flight data but it's tough when you don't know what terms to Google for more in-depth results.

Apologies if this question doesn't have a simple answer.  I'm trying to learn about HTTP requests, so I'm teaching myself by pulling flight data from websites.  Also, aviation data is new to me, so I don't realize how easy/difficult of a question this is.

Hi, Jay, Welcome to Aviation.SE! It fits our format better here if you ask only one question per "question." For more information, please see [ask] and our [help]. For now, I'm going to edit out the second question from this post so that it will fit our q/a format better.

This is the flight number. Related: What information on a specific flight can be retrieved?

These are colloquially called "flight numbers," though technically that term refers to just the numerical portion. Pretty much all travelers will use this name for them.
According to Wikipedia, the International Air Transport Association (IATA) officially uses the name "flight code" to refer to the whole portion. Unfortunately, the cited IATA document is behind a paywall, so I can't independently verify that.
In particular, the type of flight code in your example is of the ICAO variety and is also being used as the callsign for that particular flight for radio communication purposes. In the U.S., it is customary to use the airline's callsign plus the flight number as the callsign for a particular flight. Some other countries use the Aircraft Registration Code (commonly called the "tail number") of the aircraft instead of the airline flight number as the radio callsign. General aviation aircraft (which don't have airline flight numbers) will also normally use their tail number as their callsign.
When used as a call sign, a flight code will use the ICAO code for the airline. However, for purposes of airline reservation systems, it's common to see the flight number listed with the airline's (2-letter) IATA code rather than its (3-letter) ICAO code.
When a flight number is used as a callsign and is spoken on the radio, the airline's callsign will be spoken instead of the letters in the flight number. For example, your example of AWE685 will be pronounced "Cactus Six Eight Five" on the radio, since "Cactus" is the callsign for U.S. Airways.
For reference, the use of "AWE" and "Cactus" for U.S. Airways is a relic of when U.S. Airways merged with America West Airlines. They kept the name of U.S. Airways, but the ICAO code and callsign of America West (whose main hub was in Phoenix, AZ, hence the "cactus" callsign.)

It is the 'call sign' of the aircraft.
In this particular instance, the first three characters 'AWE' refers to the airline call sign (telephony designator) of the airline, America West Airlines.
The next three number refers to the flight number, which is assigned by the airline, usually based on the route. Combined together, these two form an unique identifier and is used in radio transmissions.
The list of airline codes can be seen here. However, the flight number is decided by the airlines and their website might be a good place to start.

These 3-letter codes and telephony/callsign names are officially documented by the FAA.  The most recent version is https://www.faa.gov/documentLibrary/media/Order/7340.2G_Chg_3_dtd_12-7-17.pdf but all updates are available through the Air Traffic Plans and Publications page.


text:
What is the authority in the UK?
Is the United Kingdom subject to the EASA's authority or the CAA's (Civil Aviation Authority) authority?

EASA: this is a European Union body, so yes, the UK is a member state.
CAA: There are many Civil Aviation Authorities worldwide, basically each is a national entity within the corresponding state. So, specifically for the UK, yes, there exists a body known as CAA that is a state entity, formally independent but in practice dependent on the UK Government (Dept. of Transport). Their web page is: http://www.caa.co.uk/
Due to the complex configuration of EU law, both EASA and the UK CAA can have their word to say on operations within UK territory. Though, as CAA say themselves:

The CAA works closely with the European Aviation Safety Agency (EASA) to promote the highest common standards of safety and environmental protection in civil aviation.

The last link should probably be put in as a comment, since that's an answer to a separate question that has now been edited out.

@NathanTuggy Indeed, thanks for the heads-up. For a list of all Aviation Authorities, Wikipedia has a list of CAA bodies here: https://en.wikipedia.org/wiki/List_of_civil_aviation_authorities

To update this following Brexit.
From the EASA website:
On January 1, 2021 EU aviation safety legislation, including Regulation (EU) 2018/1139 establishing EASA, no longer applies to the UK. As of that date, the UK is  considered as a third country and no longer has the status of an ‘EASA Member State’.

When you post an answer like this, it is very good that you posted the text itself (since it saves users having to follow a link in order to read the answer, and since links can change or die over time), but it's also helpful to include the link in your answer so that others can verify the authenticity of what's posted. In this case, https://www.easa.europa.eu/en/the-agency/brexit

Thank you for the info!

It's also good to use the quote markdown > to indicate quoted text, and the exact section of a referenced document makes it much easier for others to find the quote again in the future.

Noted, thank you.


text:
What are the length requirement for US aircraft N-Numbers / registrations?
Many small aircraft registered in the US seem to have a registration that follows the pattern of N, 4 numbers, and ending in a letter. Sometimes they only have 4 characters, or less. And then there's the FAA Gulfstream N1.
Who decides on what the N-Number will be, and are there requirements for how long it should be?

It's not just small aircraft in the US - all aircraft with US registration follow the same rules. The FAA has guidelines on how an N number must be formed. Basically, there are relatively few limits - you can have N + up to 5 characters, up to 2 of which can be letters (at the end).
Here's what the FAA has to say:

U.S. registration numbers may not exceed five characters in addition to the standard U.S. registration prefix letter N. These characters may be:

One to five numbers (N12345)
One to four numbers followed by one letter (N1234Z)
One to three numbers followed by two letters (N123AZ)

To avoid confusion with the numbers one and zero, the letters I and O are not to be used.
Other Requirements

An N-Number may not begin with zero. You must precede the first zero in an N-Number with any number 1 through 9. For example, N01Z is not valid.
Registration numbers N1 through N99 are strictly reserved for FAA internal use.

When an owner registers an aircraft, they can request an N number, provided it's not already registered.

N-Numbers can be reused too (e.g. N3794N)

Yes, but only if the previous registration has expired or been removed. :)

Two other answers specify the algorithm for generating valid U.S. aviation IDs.
Many who view this question might also be interested to learn that the aviation scheme is part of the entire U.S. radio station identifier scheme.  IDs beginning with AA-AL, K, N, and W are allocated to the U.S. (by ITU).  CF-CK are used in Canada, DA-DR in Germany, etc.
Commercial broadcast stations have all letters (no digits) beginning with W, K, and N; W as the first letter is used for almost all transmitters east of the Mississippi River and (mostly) K to the west.
U.S. amateur radio operators are assigned IDs with mostly letters with one digit near the front.  They are of the form L[L]DLL[L] where L is a letter and D is a digit (or occasional two digits).  [L] means an optional letter.  The whole ID is 4 or 5 characters.  The digit is assigned by class of license and region according the this scheme.
Government, scientific, civil, and other users are assigned by other unique schemes.  For example, the Oregon NOAA weather radio stations (see table of stations) all begin with 2 or 3 letters and end with 2 to 4 digits.

D is Germany, not only DA-DR. I'm pretty sure the entire C range is for Canada as well.

Standard amateur radio call signs can be up to six characters long, with a one- or two-character country prefix where one character may be a digit but one must be a letter. For example, WE1XAM would be a valid US amateur radio call sign. Prefix and suffix can be attached to this; for example, SM/WE1XAM/MM would indicate that WE1XAM is operating maritime mobile (/MM) in Sweden (SM/). 9A/WE1XAM/P would indicate portable operating (/P) in Croatia (9A/).

@falstro The ITU has assigned DS-DT to South Korea, DU-DZ to the Philippines, CA-CE to Chile, CL-CO to Cuba, etc.  Some countries (like Canada and Germany) with multiple adjacent two-letter prefixes will pretend they have a one-letter prefix but limit what the first letter of the suffix may be.

Per FAA.gov:

An N-number can be in any of these formats
One to five numbers (N12345)
One to four numbers followed by one letter (N1234Z)
One to three numbers followed by two letters (N123AZ)
N-numbers do not have

A zero (0) as the first number
The letters "I" or "O""

N1-N99 are reserved for the FAA/govt.

Someone who wants to register an aircraft, can either request a specific N number, if it's available, or they can just ask the FAA for a random one.

I used to fly N4AM (Four-Alpha-Mike) regularly.  I don't know why/how it ended up with such a short number, but it did prompt extra questions from ATC on several occasions.

Yeah, since in the US, we can shorten callsigns to the last 3 characters after initial contact, it does lead to a little confusion if someone registers their aircraft as Nnumber,2 letters.


text:
How do airlines (or the government) retrieve information from the black box of an aircraft?
When black-boxes are found, how is the information retrieved from within the data storage?  Is there a special kind of device used for this?

They send it to the manufacturer (or other lab) who knows how to get the data out.
Old black boxes stored the data on tape which they take out put in a reader and print out the data. Partially damaged tape can still be read, the result will be a data stream with holes in it.
Newer black boxes use solid state storage (like one of those 8gig memory cards). It will be put in a reader to read it out. The exact format of the data will be specific per manufacturer.
Then the analysts will make nice graphs of it for the investigators.

"other lab" usually includes the relevant local air-accident investigation organisations (e.g. AAIB, BEA) - the recorder manufacturer may only be involved if the normal means of reading the data fail.

I don't think I've ever heard they would send it to manufacturer. Usually it's either the local air-accident investigation board or they ask one of the major ones (NTSB (USA), BEA (France), MAK (Russia), AAIB (UK)) to do it (usually depending on which country the aircraft was manufactured in as that investigation board is involved anyway).

During the investigation of the Garuda Indonesia Flight 200 crash, the FDR had to be sent back to Boeing for data retrieval.

I didn't realize Boeing made FDRs...

If the blackbox is intact, procedures described in other answers would apply. If, however, the data storage device (ssd, tape, etc.) itself is damaged, it will be given to forensic experts such as police criminal unit or other expert group or company that specializes in data recovery. For them it doesn't make much difference that the storage device is in fact an aircraft flight data recorder storage, they handle it in pretty much the same manner as any other device.
Blackbox itself is unimportant, only the data on storage devices is.

Actually, the NTSB often recovers data from the blackbox. When have they ever used outside experts other than the manufacturer?

World's bigger than the U.S. and NTSB isn't  the only investigation authority.


text:
What does the small fan do that is visible on Boeing 787 Dreamliners on landing?
When watching landing videos of 787's that are in service I've been noticing a fan that is located under the right rear section of the fuselage.  I've now seen it on 4 different 787's  from 4 different airlines.
Is this an emergency fan that's deploying, or is it just something that's designed to recharge some of the batteries on board?  Some auxiliary type of system, perhaps?

do you have a photo?

I'll see if  can find one, or take a capture from the video.

(Going off of the answer below) Maybe it's just used to add more drag? Probably used on the 787 to help charge the batteries while descending... But that's just a guess. Don't take my word for it.

Any 787 pilots around here?

If you are speaking of the small fan behind the gear in the photo below (click to magnify)

Image from here.
you are speaking of a Ram Air Turbine, usually used in an emergency, not in normal operations.

Note that the above photo is taken in Settle at Boeing Field (As can be seen from the distinctive hangar in the background), indicating a test flight: the majority of the videos you see will be at the same airport, as most airlines do a few test flights with Boeing on their first delivered aircraft. Plane-spotters will often hang out here to get videos/photos of the new planes on their test flights, so you'll see an unusual number of videos of test flights (plus it's easier to get close to the runway here than at many other airports).

Why would it be used in so many landings? Is that a standard test flight landing procedure?

@Xen2050 they need to test the RAT itsefl to see there are no chewed on cables that may bring the thing down.

@Xen2050 - it isn't necessarily being used in the landing. Once the RAT has been extended on a 787, it can't be retracted again in flight. Many test flights will test the RAT, or it will be extended as a precaution during other tests. I'm unsure whether it's standard procedure to keep it extended on test flights, but it would make some sense: the nature of testing means it's nice to have backups :)

This answer would be much better if it included an explination of what a Ram Air Turbine is actually used for

I'm late to the party, but @JonStory - that's Paine Field (KPAE) in Everett, WA, where Boeing manufactures the 787.

@egid: Was just about to say the same thing.   I can confirm that is NOT KBFI (Boeing Field).  It is KPAE.


text:
Are there any best practices for transitioning from paper logbooks to electronic logbooks?
I've started flying again, and some of the things/places I fly are more interested in time in type than my old paper log shows. I'm considering going to some form of electronic logging (currently for Android and/or Linux but likely moving to iPad next year for EFB compatibility).
Question: When I start up with a new program, do I merely summarize my flight experience and ignore the tail number and a/c type? I've flown a few different birds in my time, and trying to go back through 3 logs and setting everything correctly would be a royal pain.

This question is somewhat related.

Only somewhat, and I'd read it before posing the question. I already span several logbooks, and once upon a time, I had a rather legally questionable (at the time) complete log as a dBase-4 database and app. If only I could find that old floppy... and something that'd read it...
If I had infinite time, I'd take the time to create a PostgreSQL database consistent with my needs, and do it that way. Making the schema is trivial; writing the app and associated SQL queries will drag on my available time!

Logbooks are an interesting blend of personal and professional recordkeeping.  The FAA doesn't really make a big deal about what method you use to log your flight time, just as long as you log all flight time which you're going to later use to justify currency or a new certificate.
This means that you can do whatever works best for you, as long as you (and your future employers) are happy with it.
When I transitioned to Safelog, I decided to spend a few weeks worth of evenings and just enter everything, line by line.  I did this because I had a lot of spare time, and because from now on I've got a pristine digital copy of everything, which is a nice feeling.
However, this is certainly not necessary, and there is no reason why you couldn't summarize your totals with one or a few line items.  In fact, Safelog provides a function to do exactly that: you create a pseudo-aircraft type which is defined as "summarizes several aircraft".
You can get as coarse (1,302 hours in airplanes) or as fine (389 hours in blue C-172M's with the funny starter that sounds like you just dropped a shot glass in a garbage disposal) as you want.
I would say that whatever you choose to do, just be sure that you enter it using a format which will be compatible when you switch from Android to iPad.  It's bad enough to do it once, why put yourself through the hassle of doing it twice?

The FAA doesn't really care if you log all your flight time, so long as you can show currency and compliance with applicable regulations (like aeronautical experience requirements for various ratings).  When you elect to log a flight though there are certain requirements your entry must meed :-)

Thanks, Steve. That's what I was hoping someone would propose.

Summary entries (or "starting totals") seem to be common to all logbook software and web sites; I have nothing against Safelog, but this answer could be read as implying it is unique in having this, whereas it is definitely the norm.

Also, most logbook software/web sites also allow exporting/importing via spreadsheets, which can make bulk data entry a lot easier.  You can use this to move your data from one place to another if you change your mind later, so if you do the bulk entry, at least you can be confident it's a one-time cost.

It's up to you. I started an electronic logbook just by using an excel spreadsheet which I made myself. I too entered line by line, as it's incredibly satisfying having a complete digital backup of your logbook. After a few months, I ended up buying a professional Excel spreadsheet template which worked the same as my basic one but with a whole lot more currency features etc. I got it from Excel Pilot Logbook

Does foreflight do logbooks as well?

This doesn't provide an answer to the question looking for best practices.  "Do whatever you like, I did & it worked out okay for me" isn't exactly a best practice, as the term is generally understood.

@CrossRoads, yes, ForeFlight does logs. And pretty well. I'm still trying to consider whether I'll enter everything (except my original logbook with my solo flights: lost that one!) or summarize. I have enough entries that I'd have to dedicate a fair bit of my life to accomplish it, if I don't summarize.


text:
What criteria does ATC apply to determine if an aircraft is established on the localizer if the pilot does not report it?
How close in time or distance will ATC let a pilot fly to the localizer, before cancelling the approach clearance, where the pilot has not reported being established? Is it the controller's call when to cancel the clearance?

Do you mean, when ATC will cancel the approach clearance and vector for another approach? Or do you mean when an aircraft is considered to have not captured the localizer and/or glideslope?

This question assumes that the pilot reporting established is an ATC requirement. It is not, at least not under FAA rules.

I'm not 100% sure that I understand your question, but I think you're asking this: if a pilot is on a localizer or ILS approach but doesn't report established, when will ATC cancel his clearance and instruct him to go missed or vector him? But you didn't clarify if the pilot is actually flying the approach correctly or not, where he started the approach, if he's being vectored, what his current clearance is etc. so I'm not sure I understand the scenario.
Anyway, I couldn't find a definitive, objective answer to this and I'd be surprised if there is one. If a pilot deviates from an approach procedure in any way, then the controller has to make a judgement call based on current traffic, workload, terrain, student pilots etc. and I think it's unlikely that there could be a single, definite rule on what to do when.
Apart from any other considerations, if the pilot doesn't report established it could be a comms failure and there are procedures for that: in this case since he was already cleared for the approach (presumably) the controller will expect him to continue. And if the pilot deviates without comms, there isn't much the controller can do anyway apart from clear the surrounding airspace.
Having said that, the FAA procedures for controllers give this instruction for handling aircraft on a radar arrival - i.e. under direct ATC control - and it seems plausible that they would apply it in other cases too:

b. If deviations from the final approach course are observed after
  initial course interception, apply the following:

Outside the approach gate: apply procedures in accordance with subpara a, if necessary, vector the aircraft for another approach.
Inside the approach gate: inform the pilot of the aircraft's position and ask intentions.

"subpara a" simply says that the controller should provide suitable vectors with a maximum 30° intercept angle to the final approach course. The approach gate is defined in the P/CG:

APPROACH GATE- An imaginary point used within ATC as a basis for
  vectoring aircraft to the final approach course. The gate will be
  established along the final approach course 1 mile from the final
  approach fix on the side away from the airport and will be no closer
  than 5 miles from the landing threshold.

Each instrument approach consists of a lateral part and a vertical part, in the case of the ILS approach these are: localizer and glideslope.
Aircraft are usually vectored to intercept the localizer approximately 1-2nm before the Final Approach Fix (FAF), where the glideslope is captured. Aircraft can be vectored onto the localizer as far as 20-25nm out, depending on terrain, localizer equipment and many other factors. If an aircraft is not established on the localizer, there is no point in continuing the approach, so it will be cancelled and the aircraft revectored.
If the aircraft is established on the localizer, it will try to intercept the glideslope, which is the vertical guidance system in the ILS approach. For VOR/DME, LOC/DME, NDB/DME or RNAV approaches, the vertical guidance is either achieved through correlation of location to a specific altitude in the chart or technical means which do not require a glideslope.
If an aircraft passes the Final Approach Fix and does not seem to descend, it will be considered as not established and the approach clearance will be cancelled, instructing the aircraft to either follow the missed approach procedure or manually vectoring the aircraft for another approach.

This is wrong. You won't be cleared for the approach until you've reported established.

Under which jurisdiction @rbp?

FAA http://www.faa.gov/air_traffic/publications/atpubs/atc/atc0509.html

The question was not specific for FAA airspace, it was general. Clearances for approaches without being established on a part thereof are the common case in Europe, which is what my answer is based on.

I'll see if I can find one that is not restricted in access.

if that's true, then the question can't be answered without further information. If you are talking about the full approach, then you can be cleared under FAA as well. But if you read the question carefully, this is an approach using radar vectors, in which case, you can't be cleared until you report established, because the vectors have taken you off the charted procedures, and you can't be cleared until you're back on a published Arrival procedure, or on a published segment of the approach

ATC can't give you a vector, then clear you for the approach. The vector may put you on downwind.

This is standard operations in Europe, I'll try to hunt down a quotable source. FAA and ICAO regulations differ in many areas, I assume this is one of them, because vectoring an aircraft to the approach gate and clearing them for the approach thereafter is common here. I'll get back to you.

ATC can vector them to the approach gate, but they have to report being established before issuing a clearance. do you not understand why this is a requirement?

This is not the case in Europe. What is the requirement you are referring to?

language issue: not a regulatory requirement, but a instrument procedures one. with vectors-to-final in IMC, there has to be a positive transition between the controller providing vectors and the pilot being able to continue under his own navigation. that positive transition happens when the pilot reports established, and then ATC issues the clearance. Imagine ATC vectors you to final, issues the clearance, and then you realize you're tuned to the wrong ILS. Now you're on your own navigation over the FAF with no navaid

Quoting FAA documents will not really help me find the right ICAO documents ;)

The German BAFVD (Ops Manual ATC), which is the equivalent of your FAA docs, says: "463.8  Radar vectoring will normally terminate at the time the aircraft leaves the last
assigned heading to intercept the final approach track. "
The problem is, this is not quotable, as the document is not publicly available... so my hunt continues...

OK, I misspoke. the issue is one of altitude. If ATC issues a clearance to an aircraft being vectored, the aircraft must maintain the its current altitude until it is established on a published segment of the approach. For those who want FAA info:  http://www.terps.com/ifrr/feb98.pdf and 91.175(i) http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgFAR.nsf/0/66AFE97435E47B3A86256E1A00518D27

This is the same here, but the clearance can be issued without being established, it can just not be executed by the pilot if not established or within the approach gate parameters.
" .11  The clearance for a published standard approach procedure without any
further level restrictions includes a clearance to descend to the lowest
initial approach altitude (IAF altitude) published for this standard approach
procedure."
Pilots on vectors cleared for the approach are permitted to descend to the FAF-Altitude, once established, unless the clearance includes an instruction to maintain.

91.175(i): "When operating on an unpublished route or while being radar vectored, the pilot, when an approach clearance is received, shall, in addition to complying with Sec. 91.177, maintain the last altitude assigned to that pilot until the aircraft is established on a segment of a published route or instrument approach procedure unless a different altitude is assigned by ATC. After the aircraft is so established, published altitudes apply to descent within each succeeding route or approach segment unless a different altitude is assigned by ATC."

Then what is the problem? We are talking about the same thing....


text:
How do airlines make sure that pilots remain skilled enough to operate aircraft? What quality assurance is there for certified pilots?
What measures are in place to prevent pilots from being put in charge of passenger planes without an appropriate level of training and skill? Are these measures enforced equally by different countries, airlines and aviation authorities?

Put quite simply for this answer - The Licence a pilot holds is the assurance that the pilot has received the appropriate level of training.
Each country has it's own standards for training, their own requirements, and their own limitations on the operation of that licence. In saying that, MOST countries standards are reasonably in-line in regards to Aeronautical Experience required to sit each flight test.
In Australia, the requirement to sit a Commercial Pilot Licence is a minimum of 200 hours Aeronautical Experience (150 hours if ALL training has been conducted on an Integrated Course, now to be recognized under Part 141). From there, there is a break down of what that 200/150 hours must consist of.
Now, having a Commercial Pilot Licence (again, speaking from an Australian point of view) does not give a pilot the right to sit in the left seat of an Airliner. You need further training such as;

Multi-Engine Command Instrument Rating
Type Endorsement (for the intended aircraft)
Crew Resource Management Training
Dangerous Goods Training
Senior First Aid (Not mandatory, but common)
Company, Emergency, Cyclic and Systems checks (per company)
Air Transport Pilot Licence Theory Exams (in some cases, Airlines may not even look at you if you haven't completed these - In
Australia, it is an unwritten must-have!)

And thats just to sit in as a Co-Pilot..
Captains need years of experience, and a lot more training and check to get into that coveted Left Seat.
So again, to bluntly answer your question, regardless of country, there is law in place that stipulates that Pilots must be appropriately trained to fly airliners.

You should also mention the recurrent training to make the answer complete.

Are you sure a CPL allows you to fly right seat on scheduled passenger service in Australia? This is certainly not the case here in the U.S. At least an ATP-r is required here and even then you usually have to start out on the regional carriers.

@reirab "usually have to start out on the regional carriers" makes it sound like you could be conflating legal requirements with industry/business common practices.

@Sparr Sorry for any confusion there. The ATP-r is a legal requirement. The "usually have to start out on regional carriers" is not a legal requirement, but is industry reality. The OP asked how pilot training is ensured by airlines, too, not just by laws.

It's true enough that there are laws in every country, but the legal, as well as practical, experience requirements to fly an airliner on scheduled passengers service varies dramatically between different countries. For example, ICAO has "Multi-Crew Pilot License" specification that is designed to allow relatively low-hour (i.e. starting at around 250 hr) pilots to fly SIC on an airliner, while, in the U.S., 750 is the absolute minimum requirement to fly SIC on an airliner (and that requires that you have additional previous experience as a military pilot.)

@JanHudec - The Cyclic component of Company, Emergency, Cyclic and Systems checks (per company) is where I was trying to hint at that point. :)

@reirab - Yes, you do not require an ATPL to sit in the right seat of an Airliner, as the hour and experience requirements in Australia are very high, and difficult to achieve in General Aviation. In saying that, all Australian airlines require any applicant to have all 7 ATPL exams completed, so that as soon as the flight requirements are met for at ATPL, a flight check is organised, and the Licence granted.
Also in Australia, generally you pick an Avenue (International, Domestic or Regional) and from there remain in that catergory. There is no real progression from Regional to Jet.

That is the function of a license. Every country has their own standards, and by international treaties most countries must respect the licenses issued by other countries. So, for example, a Malaysian pilot is allowed to fly in the United States, even though he has a Malaysian license and does not have an FAA license. For this reason, it may be slightly more dangerous to fly on foreign air carriers, especially if they are from sketchy, third-world countries.
Carriers have much different standards for who is allowed to captain an aircraft. For example, a big carrier like Delta will usuallly have tougher standards than a regional airline or a charter company, but not necessarily. You can find small charter companies with really tough standards, and others that will let much less experienced captains fly their aircraft.
Do not think that safety is purely a product of training and experience. You can find guys with 10,000 hours who do stupid stuff and make bumpy landings all the time and kids with 800 hours who fly ten times better than them. Skill does not necessarily = experience. Also, performance in a crisis has little to do with experience. Put one guy in a crisis and he might freeze up like a rabbit, and another cooly reacts with correct decisions. It's impossible to predict ahead of time.
In difficult situations often judgement is more important than skill or experience, although experience can help improve judgement. Examiners will try to test a pilot's judgement, but it is hard to do. It's an undefinable quantity. Once again, you can have a guy with 800 hours who has much better judgement than the long-timer Navy pilot with 10,000 hours. It's difficult to predict.

I have to disagree on some points here. Saying that flying on Foreign Carrier's is less safe than fly an American Carrier is really not true (I'm presuming your indicating American carriers by the FAA reference). Qantas in your statement above would be a foreign carrier, and according to the recently released stats and ratings for 2014, Qantas is the world's safest, and most experienced carrier, and in this case, experience relates directly to skill and safety.
Included in that Top Ten listing where Airlines such as Lufthansa and Singapore, both foreign carriers.

Thanks Tyler, I have to admit I tend to check airlines' safety records before I fly with them if they are not already known to me. I'm sure even the most lax are reasonably safe but as a nervous (yet frequent) flier I will take very safe over reasonably safe if given the option!

@JamesHam I said "sketchy third-world carriers", not Quantas. Yeah, and Swiss pilots are good too. Try flying Chanchangi Airlines in Nigeria sometime if you think foreign carriers are so safe buddy.

@Tom.  I assume that you take such precautions when choosing your mode of transport to the airport since that part of the journey is many times less safe than the most "questionable" of commercial airlines.  The only thing that would make me pause is if that airline is forbidden from flying in Aus/Europe/US.

According to Airline safety rankings, the safest airlines are non-US airlines. There's also Airline Ratings but that gives both Delta and Aeroflot the maximum score so has lower precision.

@RedGrittyBrick The problem is that most of those 'rating' schemes are extremely subjective. The link you gave rated Malaysian Airlines above American Airlines. I think that says a lot about the quality of their rankings. Furthermore, from a brief glance at their website, it looks like they're using number of incidents directly rather than comparing it to the actual size of the airline. I don't know about you, but I'd feel a little better about flying on an airline that has had one incident in 10,000,000 cycles vs. one who has had 1 incident in 100 cycles.

@reirab their indexing takes into account size of airline etc (e.g. Passenger Kilometers) but I couldn't find the exact formula (perhaps they consider it a trade-secret) "Based on our annual safety calculations which include all hull loss accidents and serious incidents in the last 30 years of operations in relation to the revenue passsenger kilometers (RPK) performed in the same time. "

@RedGrittyBrick Ah, I overlooked that at first. It wasn't listed at all on the column translation image they have at the bottom of the linked page. At any rate, larger airlines with more flight cycles still end up getting penalized somewhat just because aviation accidents are so rare that most of the smaller airlines have never actually had a fatal accident. Even being the largest airlines in the world, none of the major U.S. carriers have had a fatal accident since 2001. The regional carriers have had some (still less total fatalities than Air France alone,) but the majors haven't had any.

@reirab. I guess my real point is that the answer lacks any data or references to support the (implicit) flag-waving. What data I can find (however debatable) doesn't either.

I wouldn't really call "For this reason, it may be slightly more dangerous to fly on foreign air carriers, especially if they are from sketchy, third-world countries." flag-waving. I don't think his intent was to say that all non-U.S. airlines are less safe, just that some are (and especially the ones from third-world countries with less-than-strict aviation regulations/enforcement and generally less experience.) If I'm interpreting his intent correctly, it's pretty hard to argue that he's wrong. I would assume EU/Aussie/Kiwi carriers to be of similar safety quality as U.S. carriers.


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How do you compare private jet and commercial jet efficiency?
I'm curious about commercial airplane efficiency vs private jet efficiency.
I was trying to compare something like a modern 737 flying a full commercial flight from NYC to LA vs an Embraer Phenom 300 at full capacity (8 people) flying the same route.
I know there are many variations of the 737, so can we just use the most common commercially flown 737?
If fuel costs were the same (I understand that big airlines get discounts) is there a simple way to compare the flights simply in terms of cost of the flight, or how much fuel each plane would need for the flight? I didn't want to get into profit, crew, etc. Simply the cost of flying both planes from NYC to LA.
Thanks for any help.

You might be able to compare fuel usage but it would be hard to compare other costs (e.g. engine thrust "rental" charges, landing fees etc)

Check out Fuel Stop Planner.

This has nothing to do with private vs. commercial. The size difference is what matters.
If you compare the absolute cost of moving the aircraft from NYC to LA, the 737 will be way more expensive, regardless of version. Since you asked only which one is more expensive, I don't see a need for detailed reasoning. Just use the data provided in this answer and it becomes obvious that fuel consumption will scale with the mass of the aircraft.
If all passengers have to share the cost, the cost per passenger will be much higher in case of the Phenom 300. Or almost any other Bizjet. The Phenom will even need to land somewhere enroute to refuel. The distance from NYC to LA is bigger than the maximum range with full payload.
But that kind of comparison does not make sense - both airplanes have been designed for different purposes, so their strengths are in their unique field of use. They do not transfer well to that of different aircraft types.

The cost per passenger will be much more in case of Phenom 300. See also http://aviation.stackexchange.com/questions/8130/cost-per-seat-mile-commercial-vs-private-jets.

Thank you. I know they don't compare very well and are designed for different purposes I was just trying to compare figures for curiositys sake.

@JanHudec: Big typo, now corrected. Thanks for the remark!

Hourly fuel costs for a private jet can run from 800-2000/hr USD.  So the 5 hours from NY-LA range from 4,000 to 10,000.  But fuel is only part of the equation.  On also has to figure in cost of ownership issues such as parking/hangar, insurance, engine reserves, avionics reserves, annual inspection reserve, etc.  Also there are additional direct operating costs such as pilot salaries, crew salaries, tied down/gate fees.
For some fractional ownership programs where all of this is loaded it is not uncommon to end up with a 4,000-8,000/hr figure.  This assumes you have already made a fractional payment of around 200,000-500,000 depending upon type of plane and percentage of ownership share (1/6, 1/12, ...).
There are also other programs where you rent the jet, crew, etc, but I have not looked at those figures.

Simply the cost of flying both planes from NYC to LA

The 737 will cost a lot more than the 8-seat bizjet. This kind of comparison is just about useless - direct cost per seat-kilometer is as basic as you can get, and even that one is very rough.
Crew and maintenance are inescapable costs so excluding them makes the calculations even more skewed. Landing fees are based on gross weight class divided into the number of passengers, facility fees are actual number of passengers on board, parking is by size, navigation is based on ability-to-pay (the 737 pays, because it's a commercial flight. A privately owned Cessna gets ATC for free). The bizjet can use smaller airfields that can be hours closer to the group's destination so once you factor in ground transportation (and lower airport fees) and employee time the bizjet can actually work out cheaper per seat than Delta. But you do have to consider everything.

Thanks for your input. Is there an easy way to compare the cost of such flights if they were both commercial? I know the big airlines aren't really flying Phenomes but if there was a way to ballpark the cost either total or as you said cost per seat-km/mi

Private flights can be dramatically cheaper for non-hub flights.  A few years back we planned a trip that could be done airline or private.  Airline quoted $650 a piece round trip.  Private the costs when split among the 6 of us worked out to only 10% of that and was a 2 hour flight instead of the commercial 6 hour trip (with 2 flights and a layover)!

What does it mean that "navigation is based on ability to pay"? At least in the US, I thought that there are no user fees for ATC, it's all paid for via taxation. So everyone gets ATC "for free", although everyone also pays via fuel and other taxes.

I just found this list of various plane models and information about them such as average fuel burn and total variable cost/hour. If anyone is interested: http://www.duncanaviation.aero/files/aircraft_sales/Business-Jet-Model-Market-Summary.pdf


text:
What flaps position should be used for taking off from a wet runway?
If I have to take off in a C152 or C172 from a runway that's 800-900 meters (2600-3000ft) long and wet but not contaminated, what flap setting should I use to get the shortest ground roll?

Flaps will shorten the takeoff roll at the expense of climb performance, see https://www.experimentalaircraft.info/flight-planning/aircraft-performance-5.php

I learned how to fly in a 152 and a 172 on a field that was only 1900 ft long, or about 580 meters. I never had any issues with even a wet runway. I'd recommend using the exact same procedures as you normally would.

I would second this. In my experience with C152, there was no noticeable difference while taking off from a wet runway instead of a dry runway, although the instances of wet runway were few and far between for obvious reasons.

Why would a wet runway be even s consideration?

"Why would a wet runway be even a consideration" -- steering?  Not in actual practice it seems.  The question would be more interesting if it asked about an ICY runway...

The POH for a 152 lists the flap settings for takeoff as between 0° and 10°. It makes no specific mention of take off from a wet runway, however you could follow the same procedures for a soft/rough runway if you are concerned about the surface conditions.

Soft or rough field take off are performed with 10° wing flaps by lifting the aircraft off the ground as soon as practical in a slightly tail low attitude. If no obstacles are ahead, the airplane should be leveled off immediately to accelerate to a higher climb speed

Source: Cessna 152 POH Section4 (Normal procedures)
I should note though that in roughly 180 hours on C150/152's and a short (650m) hard runway, I've never felt the need to even use flaps, let alone execute a soft/rough field takeoff as described above. It's not a particularly comfortable take off, and a wet hard-surface runway doesn't really present that much of a problem.

Wet is such a varied expression. How much water are we talking about ? Just a little wet, some water puddles, or the whole runway has a few mm of water all the way through ?
Realize tires on such planes aren't that dissimilar to car tires. Can you drive at takeoff speeds without feeling the water is dragging the car ? If you can, you fly and take off the same. Try this out on a road near the airport (which received the same volume of precip and is just as flat as the runway).
I'd use first notch of flaps and would hold the aircraft until full power is achieved and then release so you don't waste any runway distance.
Doesn't matter if the runway is slippery. What matters is if the water produces significant extra tire drag that reduces acceleration. Probably obvious by might not be to others.
250 hours flying C150/152/172. Very few takeoff / landings on wet runways.
Look up the POH and make sure you have some extra runway length to spare just in case.

well wet runway means a runway with 3 mm of standing water or less in less than 25 % of the runway usable for take-off. In the POH there is no mention about a take-off on wet runway and which flap setting is recommended, for that reason I asked. Probably someone has tried to take-off with different flap setting and could give me some tips from their experience. I know that every take-off are different from each other for the too many variables included. It was just to share some experience with other pilots.

If the runway is very wet you could try a short field technique meaning you're trying to lift off as quickly as possible, accelerate on ground effect then get the climb going.


text:
What are the drawbacks of a liquid hydrogen jet engine?
I am looking into building a jet aircraft utilizing liquid hydrogen as a fuel source. I have already built a few original design pulse jets, and I'm looking for a new project.  Cryogenic fuel jet engines look good, but I feel there may be drawbacks.

See https://en.wikipedia.org/wiki/Hydrogen-powered_aircraft

Welcome! The title and the body of your question follow different directions: Title: LH2 used for cooling, body LH2 used for combustion. Could you clarify?

@mins I edited the title. I believe the OP mean that the fuel is cryogenically cooled and not the engine

The biggest drawback is keeping the fuel in a liquid state. This requires a very complex cryogenic cooling and storage system. Also, if the aircraft crashes, expect a really big fireball with no survivors.

1: Cryogenic fuel
2: Reactivity with alloys aircraft construction
3. Engine damage and high temperatures

Related (LH2 is used for space exploration since many years): Explosive lessons in hydrogen safety - NASA // and // Assessment of crash fire hazard of LH2 fueled aircraft

Here are a few drawbacks:

Lesser energy density per volume

For the same amount of energy, you need more space, not yet available in current designs

Boil off

The hydrogen will slowly boil off, and vented to the atmosphere. Hydrogen IS dangerous, and this will negatively impact long flights.

Logistics

Fuel is common everywhere in the world and easy to store. We have yet to build a world delivery network for hydrogen.

@reirab on It is not.  I edited the bullet point to clarify, but if you read the sub text you'll see that I was clearly speaking about density per mass and not per kg. So yes the fuel will weight less but take a huge amount of space.

Ah, yeah, sorry, missed that part. When I see "energy density" I normally think per mass. The volumetric energy density of LH2 is only around a quarter of that of jet fuel.


text:
will a Sears-Haack body straighten itself out if "launched" sideways?
I'm asking this here not because it's a question about flying a plane but because I read some engineering questions that said to bring aerodynamics questions to aviation.se for the best results.
Will a Sears-Haack body straighten itself out if "launched" sideways? Let's say it's launched from space toward the earth and hits the atmosphere at supersonic speeds. Even if it "hit" air side-on would it straighten itself out? (That is -- one of the pointy-sides now at the front) And if so would it happen in a quick/undramatic way so that the spaceship launching it would have a reasonable chance of hitting an intended destination?
If not, would the addition of fins to one end make it more likely to right itself as it hit the air?
--I guess this question boils down to: "will an object moving at high speed find and stay in its most aerodynamic orientation?" and then: "if not, will a major control surface like fins make it do so?"

Welcome to Aviation.SE and thanks for the interesting first question!

will an object moving at high speed find and stay in its most aerodynamic orientation?

No. It will most likely tumble around. With the center of gravity behind its center of pressure, a body of rotation is inherently unstable.

if not, will a major control surface like fins make it do so?

Yes. That is the reason for those large surfaces at the rear end of airplanes.
This answer is about directional stability over Mach. At supersonic speed directional stability drops with increasing Mach number.
This answer covers a similar topic; now it is about the proper location of fins at supersonic speed.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
What does a typical discovery flight consist of?
I've been considering taking up flying as a hobby and have been looking into flight schools around me. One does offer an option of a discovery flight but upon contacting them they really didn't pass along to much information on what it consist of. Could someone here kind of give me an example of what a discovery flight might consist of and help me know what to expect. Thank you!

A typical discovery flight is about a 30 minute on the ground introduction to the airplane and the cockpit controls, followed by a sightseeing flight of 30-minutes to one-hour.  The entire process typically lasts 1 to 2 hours.
During the flight, the instructor will have the controls for takeoff, navigation and landing, but may turn the controls over to the passenger for some gentle, easy maneuvers.
You can expect to ask numerous questions and have them answered, but you won't learn a whole lot about actual flying in a short session.
I would advise you to keep your questions to the flight training process, rather than specifics about flying that need more detailed explanations.
Some good questions may be:
How much ground school does it take to get a license?
How much flight time does it take to get a license?
What are some important milestones along the way to getting a license?
Will I have the same instructor throughout my training?
What supplies do I need for training? How much should I expect to spend?

thanks for the reply definitely gives me some ideas on what to expect.

+1 for asking about the training process more than the flying

You may also 'discover' that flying in small aircraft isn't for you. Flying in a small plane may terrify you or you may get air sick. Flying in small planes isn't for everyone. I started flight training with a friend. He would get airsick and gave up on learning to fly. Needless to say, sometimes flying in a small plane still scares me.

@NKlosterman yes thats part of my interest in taking a discovery flight. I used to fly from time to time in my grandfathers plane but I was a lot younger.

But don't let initial discomfort discourage you.   I got vertigo/airsick/disoriented on my discovery flight, but after another few hours of flight training, I was fine.

@abelenky I'll keep that in mind, I've never had that happen before but its also been quite a while since I was in a smaller plane.

I would focus more on the performance of the instructor when asking those questions: "How much ground school do your students typically need?", or "How much flight time do your students typically need?". A quick check of the FARs will reveal the 40-hour minimum flight time, but that's not very useful if none of the instructor's students finished with less than 80 hours. Remember, you as a potential student are essentially interviewing the instructor for a job; like any other job applicant, you want to find the best one you can. Past performance is about as good an indicator there is here.

On my discovery flight the instructor asked me what I wanted to do. He said a lot of people take a sightseeing flight around the city. I opted to do some actual flying.
After a thorough pre-flight and a run-through of the controls and basic instruments (it was a C172, basic 6-pack steam gauges) we ran the checklists, taxied to the runway, did the run-up and were cleared by the tower. He took care of all the communications for the flight.
The instructor did the first takeoff and just had me hold my hands on the yoke to feel what he was doing. We flew to a nearby airport and did a touch-and-go. This time he let me do the takeoff myself while he kept his hands on the yoke.
He had me fly the pattern and do two more touch-and-go's. Each time he let me do a bit more on the landing. He would tell me when to add flaps, when to throttle up and down, and when to cut power to touch down. Then we flew back to the base airport and I did the landing myself. Of course, he had his hands on the yoke during the landing in case I tried to do something stupid.
It was a calm day and I was quite surprised how easy the plane was to handle. I was too high on one approach so he took the controls for a few seconds and did a forward slip to get me back in position.
The flight was for an hour of Hobbs time, of which I used about 50 min. The calm winds were a big factor. He wouldn't have been able to let me be so hands-on if there had been wind too deal with.

Interesting, sounds like a really neat introduction to flying.

Yeah, my first flight was more like this. After we went through the pre-flight and engine start checklists, my instructor basically told me, "Ok, now taxi to the runway and take off." (Of course, this was an uncontrolled field, not a towered one.) He did the comms for that flight, though.

@reirab It helped immensely that I had spent so much time on here. I had the majority of the "book" learning down. I already knew things like adding rudder to keep the ball centered, on approach use pitch for airspeed and power for vertical speed without having to be told. I only made one mistake that scared us both for a split second.

@TomMcW Yeah, I already knew most of the basic stuff before my first flight, too, which my instructor knew (I had known him for quite a while before the flight.) Otherwise, I'm sure he would have taken it much more slowly. He only touched the controls a few times during the hour (one of them being to demonstrate a stall.)

@reirab I wanted to have the instructor demonstrate a stall for me and when I got up there I forgot to ask.


text:
What is the purpose of anti-skid surge accumulator in a 777-300?
What is the purpose of the anti-skid surge accumulator in a Boeing 777-300?
What would happen if it were not present and why is it only meant for the left landing gear wheel assembly?

Is it homework? When you ask for help on homework, you need to show you made a significant effort, and you were able to get some elements, but not enough, to understand the question asked. We do not do homework from scratch.

@mins nah its not homework .

Looks like you missed part 1 of your question. Having them numbered that way may cause some (or many) to think they're homework questions...

I'm voting to close this question as off-topic because it looks like homework with no effort to reformat, and no effort to partially answer. You may edit your question so that it looks more motivated by personal interest.

@FreeMan I thought that, too, at first, but I think "part 1" is intended to be the question title.

@Squareoot This question is now the #1 Google hit. #2 is unrelated (it's about a surge suppressor.) #3 might have something useful, but it's about the KC-135, not the 773. #4 is a syndication of this question. Apparently Otto reposts our questions on p3air.com

@reirab i am a Trainee technician.New to the field.. just started working on B777 with no prior experience. Spend most of my time studying manuals. Thats where i got the question from.  I can't ask any superior because they aren't that interesed about what and why . Got to ask someoone.

@Pritam Ah, ok, thanks for clarifying. Welcome to Aviation.SE! I hope someone here is able to answer your question.

When an aircraft touches the ground, brakes are applied to decelerate the aircraft. To execute this
on an efficient manner, an anti-skid system is installed. This makes it possible for the aircraft to perform
a stop with maximal deceleration and minimal wear of the tires. In this way the aircraft can
come to a safe stop without unnecessary maintenance.

Further info: https://anoukaviation.files.wordpress.com/2009/07/project-report-landing-gear.pdf (search for skid)

The anti-skid surge accumulator absorbs brake release surges from the left normal anti-skid valve module.
The right normal antiskid valve module does not need an antiskid surge accumulator because the right hydraulic system reservoir is very near to the right normal antiskid valve module.

From: http://www.plane.cc/html/ziliao/jiwu/2011/0426/23491_33.html